Since the 1970's there has been a great need to use rapidly moving doors in buildings for industrial use, collectively referred to as industrial doors. This applies to openings indoors as well as in external walls, where the door provides shielding between different activities or prevents drafts and heat losses. It is well known in the door industry to provide a flexible, roll-up door that can be used to provide a passageway barrier in industrial, commercial, mining and other such facilities to accommodate the access of trucks, trains, forklifts and other such equipment to the facility or building or to provide passageway barriers within the facility or building.
Roll-up doors formed with flexible door leaves are often used for this purpose, but more rigid constructions like slatted doors with polymeric or metallic lamellae are also used. In one known example, these doors are rolled up on an overhead drive cylinder or on two independently driven disks and can be provided with additional elements like transverse wind reinforcements on the door leaf to counteract wind load, a weight balance system, tensioning system, windows or the like. For safety reasons, roll-up doors can be further provided with safety edge protection, failsafe devices, drop protection, and crash safety functions.
A flexible roll-up door typically consists of a synthetic rubber or fabric curtain, or belting panel material, which acts as a barrier across the passageway. The curtain is attached across its top edge to a rigid metal drum spanning the width of the passageway. This metal drum is typically known as a drive barrel and is equipped with a solid steel shaft at both ends. Each of the two steel shafts are supported by a flanged type bearing attached to a steel plate, typically known as an endplate, which is attached to the side frames or building structure directly around the passageway. Applying a controlled rotational movement of the drive barrel results in the curtain spooling onto the drive barrel, thus retracting the curtain upward to expose the passageway. Also, it may be inversely spooled off the drive barrel to dispense the curtain downward and close off the passageway.
The lower, horizontal perimeter or bottom of the curtain is reinforced with structural steel members to provide rigidity to the section of curtain edge making contact with the ground. This component of a flexible roll-up door is typically known as a bottom bar and must be of sufficient rigidity to maintain adequate straightness of the curtain for the operation of the door. The bottom bar is configured to a predetermined mass to provide adequate gravitational force to pull the curtain to the ground. The bottom bar may include reversing, safety and/or sealing devices mounted thereon.
The two vertical perimeters or edge sections of the curtain usually travel within suitable enclosures mounted adjacent to the passageway on each side. This component is typically known as a guide and serves the purpose of maintaining the required position of the vertical edge of the curtain while permitting unrestricted travel during door operation. The curtain is most often configured along its vertical edges with appropriate components, hereto referred to as curtain locks, to mate with the guides. Many flexible roll-up doors are constructed so that a predetermined releasing force can-cause the curtain to disengage itself from the guide or guides, for example, when the curtain is impacted by a vehicle or other device. The curtain is both retracted by and dispensed from the drive barrel over the forward side of a horizontal, rigid steel pipe spanning the width of the passageway. This pipe is located above the passageway and in close proximity to the building structure to provide an upper horizontal perimeter seal to the passageway and further serves as a curtain positioning mechanism, aligning the curtain with the guides mounted to the vertical sides of the passageway. This steel pipe is typically known as an idler barrel and is equipped with a solid steel shaft at both ends. Each of the two steel shafts are supported by a flange type bearing attached to its respective mounting angle.
The known flexible roll-up door systems can also include various other components to complete their functionality such as a counterbalance system, often through the use of torsion springs and/or weights, an operating mechanism that may consist of a manual hoist and/or electric motor with gear and/or chain power transmission arrangement, along with other secondary components. Known roll-up doors are commonly equipped with a curtain that has an element or elements attached to the vertical edges of the curtain (forming a curtain lock or windlocks) that co-operate with fabricated, often elaborate, guide assemblies. U.S. Pat. No. 7,516,770, U.S. Pat. No. 5,445,209, and U.S. Pat. No. 5,482,104, for example, disclose roll-up door systems with such guide assemblies.
As disclosed in these patents, it is desirable to provide a structure which enables the side edges of the flexible curtain to separate from the guide structure in the event the flexible curtain is subjected to an excessive impact force such as a vehicle striking the door but withstand wind or air pressure without disengagement from the guide. Flexible roll-up doors with continuous windlocks can retain the door panel horizontally inside the guides and provide a seal. However, these windlocks become wedged in rigid guides if the force is too great and cannot be laterally reinserted without an even greater force, special tools, or partial or full disassembly of the structure. The structures resisting the pull-out force of the flexible door panel are also designed to require rigidity and minimize deflection in all components such that elastic deformation in the support frames, usually metal, must occur in order to allow the flexible panel windlocks to dislodge.
This problem has typically been solved by either fully or partially disassembling the rigid vertical guide system to dislodge or reduce the force on the windlocks, or by using segmented, relieved, or non-continuous windlocks. Some designs have used discrete, incrementally located, rigid or semi-rigid fasteners attached to the flexible curtain. In all known cases, however, reinsertion of the flexible panel and windlocks into their normal state in the vertical guide is prevented horizontally by design.